Incorrect size of first autocomple in Inlines with "collapsed" class

[Michał Pokusa]

This error occurs on versions after removing the "collapse.js" and moving to <details> and <summary> tags, mainly Django>=5.1 and in my opinion is purely JS/CSS related and Python independent. This happens using both StackedInline and TabularInline.

Tested on Google Chrome, Firefox, Edge, Brave and Safari, but with inconsistnt results, seems like the problems is mainly on desktop, but also on mobile devides when using desktop mode with sidebar open (I know how it sounds, but it might be caused by some element width checking).

Desktop:

Mobile (Chrome):

Steps to reproduce:

models.py

from django.db import models


class Restaurant(models.Model):
    name = models.CharField(max_length=100)
    address = models.CharField(max_length=255)

    def __str__(self):
        return self.name


class Order(models.Model):
    restaurant = models.ForeignKey(Restaurant, on_delete=models.CASCADE)
    order_number = models.CharField(max_length=20)
    products = models.ManyToManyField("Product", related_name="orders")

    def __str__(self):
        return f"Order {self.pk} from {self.restaurant.name}"


class Product(models.Model):
    name = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=10, decimal_places=2)

    def __str__(self):
        return f"{self.name} - ${self.price}"

admin.py

from django.contrib import admin

from .models import Restaurant, Order, Product


class OrderInline(admin.StackedInline):
    model = Order
    extra = 3

    fields = ["order_number", "products"]
    autocomplete_fields = ["products"]

    classes = ["collapse"]


@admin.register(Restaurant)
class RestaurantAdmin(admin.ModelAdmin):
    list_display = ("name", "address")
    search_fields = ("name", "address")

    inlines = [OrderInline]


@admin.register(Order)
class OrderAdmin(admin.ModelAdmin):
    list_display = ("restaurant", "order_number")


@admin.register(Product)
class ProductAdmin(admin.ModelAdmin):
    list_display = ("name", "price")

    search_fields = ("name",)